1. Field of the Invention
The present invention relates generally to an image forming apparatus utilizing an electrophotographic technique such as a printer and a copying machine, and more particularly, to an image forming apparatus so adapted to bring a charging brush (which means a brush for carrying out charging) into contact with the surface of an image carrier (which means holding an electrostatic latent image holding member on which an electrostatic latent image is formed) to charge the image carrier to a predetermined polarity, form an electrostatic latent image corresponding to image information on the surface of the image carrier thus charged by latent image forming means, and supply toner to the surface of the image carrier having the electrostatic latent image thus formed thereon from a developing device, to develop the electrostatic latent image thus formed on the surface of the image carrier into a toner image (which means forming a toner image corresponding to the electrostatic latent image).
2. Description of Related Art
Conventionally, an image forming apparatus utilizing an electrophotographic technique such as a printer and a copying machine has been generally so adapted to charge an image carrier by the corona discharge method, form an electrostatic latent image corresponding to image information on the surface of the image carrier thus charged by latent image forming means, and supply toner to the surface of the image carrier having the electrostatic latent image formed thereon, to develop the electrostatic latent image formed on the surface of the image carrier into a toner image.
When the image carrier is charged by the corona discharge method as described above, however, harmful ozone is generated when corona discharging is carried out, and a power supply for outputting a high voltage is required to carry out the corona discharging, resulting in a high manufacturing cost.
In recent years, therefore, a method of charging an image carrier at a low voltage has been examined in addition to the above described corona discharge method for charging an image carrier using a power supply for outputting a high voltage. As a method of charging an image carrier at a low voltage, a method of bringing a charging brush into contact with the surface of an image carrier to charge the image carrier has been developed.
However, the method of bringing a charging brush into contact with the surface of an image carrier to charge the image carrier has not been satisfactorily examined yet. The method has not been generalized in the present circumstances because it has the disadvantages, for example, in that toner remaining on the image carrier is accumulated in the charging brush by adhesion, the image carrier is not uniformly charged, and the image carrier is filmed with the toner thus accumulated in the charging brush by adhesion.